Scheduling flying crews of airline companies is a hard combinatorial problem, taken the complexity of constraints that have to be satisfied. Constraint-based programming techniques is a new method, apart to the traditional Operations Research-based techniques used so far for the solution of the problem. The presentation will discuss the findings and results of applying constraint-based programming techniques and associated tools for the solution of the crew scheduling problem in the context of the ESPRIT HPCN project PARACHUTE, a project that combines constraint programming with parallel computing. 1 Introduction The major difficulty of the combinatorial optimization problems is the size of the problem search space. Finding the optimal solution is a very demanding task which implies the testing of every possible solution as a candidate for being an optimal solution. A simple method to achieve this, is the "generate and test" method. This method invokes the generation of all possible ...